1. Field of the Invention
The present invention relates to a storage medium having stored thereon a game program for causing a computer of a game apparatus to execute game processing based on an input value which changes in accordance with the motion of an input device itself, and a game apparatus; and more specifically to detection of a motion of the input device itself.
2. Description of the Background Art
Conventionally, a game system by which a player can enjoy moving an input device itself (controller) using an acceleration sensor has been proposed. For example, a shooting game using a gun-type controller having a built-in acceleration sensor has been proposed (for example, Japanese Laid-Open Patent Publication No. 2000-300843). In this shooting game, the moving direction of the gun-type controller is detected by the acceleration sensor. When the player moves the gun-type controller rightward by mimicking the motion of opening the revolver of the gun, an image of bullets is displayed on the monitor, so that the player can confirm the remaining number of bullets. When the player moves the gun-type controller up and down in this state, the gun can be additionally loaded. When the player moves the gun-type controller leftward by mimicking the motion of closing the revolver, the image of bullets disappears. In this manner, the moving direction of the gun-type controller is determined by the acceleration sensor, and game processing in accordance with the moving direction is executed.
A game of determining an impact which is input to a mobile game apparatus itself using an acceleration sensor has been proposed (for example, Japanese Laid-Open Patent Publication No. 2001-170358). In this game, a change in the magnitude or direction of acceleration applied to a game apparatus (housing) is detected, and how much output has been made in which axial direction is determined. For example, when the game apparatus is slid in an X-axis direction, an acceleration is generated. Based on the X-axis output of the acceleration sensor, the movement in the X-axis direction (sliding movement) is determined. If, at this point, the X-axis output has a value equal to or greater than a predetermined value, it is determined that an impact input has been made. For example, when an acceleration having a value equal to or greater than the predetermined value is detected in a positive X-axis direction, it is determined that an impact input from the left has been made. When an acceleration having a value equal to or greater than the predetermined value is detected in a negative X-axis direction, it is determined that an impact input from the right has been made.
However, the conventional game apparatuses described in the above-mentioned publications have the following problems. With the game disclosed in Japanese Laid-Open Patent Publication No. 2000-300843, it is determined at how much strength, and in which direction, the gun-type controller itself was moved. It is impossible to accurately determine whether the operation made by the player is an operation of, for example, swinging the gun-type controller or an operation of applying an impact to the gun-type controller.
With the game apparatus disclosed in Japanese Laid-Open Patent Publication No. 2001-170358, it is determined whether or not an impact input was made by determining whether the magnitude of acceleration is equal to or greater than a predetermined value. However, even when an operation of moving the game apparatus is made, an acceleration having a value equal to or greater than the predetermined value may be detected (when, for example, the player makes an operation of strongly swinging the game apparatus). This may be incorrectly recognized as an impact input. Thus, when an acceleration having a value equal to or greater than the predetermined value is detected, it is difficult to precisely determine whether the player makes a motion of moving the game apparatus (strongly swings the game apparatus) or applies an impact to the game apparatus.